1. Field of the Invention
The present invention relates to propagation environment notification methods and notification systems in radio communication systems, and media recording control programs thereof, and particularly relates to propagation environment notification methods and notification systems in radio communication systems in which user specific conditions such as a user's area layout and placement of a radio base station are inputted via a network such as Internet to provide information of radio propagation environment in each user's area based on expert knowledge, and record media recording programs thereof.
2. Description of the Prior Art
The base station placement design for a radio communication system constituted by radio base stations and radio terminals in an environment where obstacles exist, like an environment where appliances such as desks/shelves are placed depending on user's preferences, is a design matter involving expert knowledge. In this environment, influences such as reflection and refraction of radio waves by obstacles vary depending on the placement of the base station, and thus significant variation occurs as to shadow areas where communication is impossible.
For example, an indoor environment as shown in FIG. 13 will be considered. FIG. 13 shows one example of an area where radio communication is impossible. In this figure, reference numerals 1000-1 to 1000-4 denote walls, by which one indoor environment is defined. Also, reference numerals 1001-1 to 1001-3 denote partitions partitioning respective rooms. In addition, as appliances, desks denoted by reference numerals 1003-1 to 1003-3, a shelf denoted by reference numeral 1002, and a sofa denoted by reference numeral 1004 are provided. In this indoor environment, if a radio base station 1010 is placed on the desk 1003-1, for example, a hatched area in this figure at some distance from the radio base station 1010 becomes a shadow area, in which communication is impossible.
Also, it can be considered that if the radio base station 1010 is placed on the desk 1003-2, shadow areas (hatched area in this figure) are created, for example, near the walls 1000-4 and 1000-1, and communication therein becomes impossible, as shown in FIG. 14 showing a second example of areas where radio communication becomes impossible. These hatched areas depend on the walls 1000-1 to 1000-4, partitions 1001-1 to 1001-3, the materials of appliances, the placement of appliances and the distance between partitions, and thus it is difficult for users who have no expert knowledge to predict shadow areas.
On the other hand, for solving these problems of placing stations of radio systems, a base station setting system in which a plurality of predefined base station placement candidate points is defined for a predefined service providing area in a building, and then a base station placement candidate point is selected and a notification thereof is made so that the entire service area can be covered is disclosed in Japanese Patent Laid-Open No. 7-87557 (hereinafter referred to as Document 1), for example. Also, in Japanese Patent Laid-Open No. 8-214363 (herein after referred to as Document 2), a method is disclosed in which base station placement points are determined one after another in such a manner that radio shadow areas are reduced, in order to determine the placement of the base station allowing no radio shadow areas to occur.
These systems shown in Documents 1 and 2 basically minimize radio shadow areas, based on the magnitude of receipt electric power. Furthermore, as shown in Japanese Patent Laid-Open No. 5-226853 (hereinafter referred to as Document 3), a base station setting system in which a plurality of predefined base station placement candidate points is defined for a predefined service providing area in a building, and then a base station placement candidate point is selected and a notification thereof is made so that the entire service area can be covered is known. Also, in Japanese Patent Laid-Open No. 7-036063(hereinafter referred to as Document 4), a method is shown in which base station placement points are determined one after another in such a manner that radio shadow areas are reduced, in order to determine the placement of the base station allowing no radio shadow areas to occur. These systems basically minimize radio shadow areas, based on the magnitude of receipt electric power.